DATA GIVEN:

Mass of propane = 120.0g
Molar mass of propane = 44g/mole
Asked:
Mass of water formed equation
C₃ + 5O₂ → 3CO₂ + 4H₂
1 mole: 5 moles: 3 moles: 4 moles

SOLUTION

To convert 120.0g of propane into mole.
Mole = mass /Molar mass
= 120g /44g/mole
= 2.727 mole

To make mole equivalent between propane and water.
1mole of C₃H₈ Ξ 4 moles of H₂O
2.727 mole of C₃ Ξ ?? of H₂O

= 2.727 mole × 4 moles /1 mole
= 10.9 mole of H₂O

Mass of H₂O = mole × molar mass
= 10.9 moles × 18g/mole
= 196.36g
196.36g of water (H₂O) was formed.